// Copyright 2022 ByteDance and its affiliates.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package filters

import (
	"net/http"

	"k8s.io/apimachinery/pkg/util/runtime"
	"k8s.io/klog"
)

// WithNoLoggingPanicRecovery wraps an http Handler to recover and log panics (except in the special case of http.ErrAbortHandler panics, which suppress logging).
func WithNoLoggingPanicRecovery(handler http.Handler) http.Handler {
	return withNoLoggingPanicRecovery(handler, func(w http.ResponseWriter, req *http.Request, err interface{}) {
		if err == http.ErrAbortHandler {
			// honor the http.ErrAbortHandler sentinel panic value:
			//   ErrAbortHandler is a sentinel panic value to abort a handler.
			//   While any panic from ServeHTTP aborts the response to the client,
			//   panicking with ErrAbortHandler also suppresses logging of a stack trace to the server's error log.
			return
		}
		http.Error(w, "This request caused apiserver to panic. Look in the logs for details.", http.StatusInternalServerError)
		klog.Errorf("apiserver panic'd on %v %v", req.Method, req.RequestURI)
	})
}

func withNoLoggingPanicRecovery(handler http.Handler, crashHandler func(http.ResponseWriter, *http.Request, interface{})) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
		defer runtime.HandleCrash(func(err interface{}) {
			crashHandler(w, req, err)
		})

		// Dispatch to the internal handler
		handler.ServeHTTP(w, req)
	})
}
